The burning of petroleum-based fuels, such as diesel fuel, is known to contribute to poor air quality. As a result, efforts have been undertaken to develop engines, and their associated machines, that can operate using alternative fuels. Such alternative fuels, which may burn cleaner than petroleum-based fuels, may include, for example, natural gas, propane, methanol, ethanol, hydrogen, and biodiesel. Some development efforts have focused on providing cost-effective and reliable alternatives to petroleum-based fuels, while also utilizing the performance and efficiency advantages of compression ignition engines. Thus, one such alternative strategy includes configuring a compression ignition engine to operate using both diesel fuel and natural gas fuel. For example, small amounts of diesel fuel may be used to compression ignite the combined diesel fuel and natural gas fuel.
Natural gas fuel may be stored onboard the machine in a liquefied state in order to achieve a higher storage density. However, the use of such a cryogenic fuel requires the use of specialized equipment, including a cryogenic tank for storing the liquefied natural gas fuel and a cryogenic pump for withdrawing and pressurizing the liquefied natural gas fuel. These components, the performance of which can be critical to engine operation, are susceptible to problems that may gradually become worse over time. Therefore, it may be desirable to repair or replace damaged components soon after the problem is detected, and before the problem progresses to component failure and renders the engine and machine inoperable. However, detecting the problem early is a significant challenge.
An exemplary diagnostics method for diagnosing cryogenic pump performance is provided in U.S. Pat. No. 7,913,496 to Batenburg et al. In particular, the Batenburg et al. reference teaches the use of a pressure sensor positioned downstream from the cryogenic pump along a delivery conduit between the cryogenic pump and an engine fuel injector. More specifically, the pressure sensor is positioned downstream from a heater, which changes the liquefied natural gas into a gaseous state, and upstream from an accumulator, which stores the natural gas in the gaseous state. An electronic controller is configured to receive a pressure signal from the pressure sensor and determine whether cryogenic pump performance has degraded by comparing the measured rate of fluid pressure increase to typical fluid pressure increases along the delivery conduit. Specifically, a problem with the cryogenic pump may be indicated if the measured rate of fluid pressure increase is lower than expected. Thus, while the art recognizes a need to diagnose cryogenic pump problems, there is a continuing need to provide cost-effective and reliable means for diagnosing problems with cryogenic fuel system components.
The present disclosure is directed to one or more of the problems or issues set forth above.